TRAPPED IONS GROUP
Probing QED and fundamental constants through laser spectroscopy of vibrational transitions in HD+.
Nat. Commun. 7, 10385 (2016)
Photodissociation of trapped H2+ ions for REMPD spectroscopy.
Appl. Phys. B 107, 1043 (2012)
Narrow-line phase-locked quantum cascade laser in the 9.2 µm range.
Opt. Lett. 32, 1641 (2007)
Thomas Louvradoux (PhD)
Julian Schmidt (Postdoc)
The existence of narrow transitions between long-lived vibrational levels, and the possibility of accurate quantum electrodynamics calculations, make laser spectroscopy of the H2+ and HD+ molecular ions a sensitive tool to test fundamental physics at the molecular scale.
One of the possible outcomes, taking advantage of the dependence of the vibration frequency on the proton’s mass, is an improved determination of the proton-to-electron mass ratio.
We are setting up an experiment to observe and measure a two-photon transition between the two lowest vibrational states (v=0 and v=1) of H2+.
The ions are selectively created in the ground vibrational state by resonance-enhanced multiphoton ionization (REMPI) of H2 and held in a linear radiofrequency trap, where they are sympathetically cooled to millikelvin temperatures by laser-cooled Be+ ions.
Detection of the transition relies on selective photo-dissociation of the excited state by a UV laser.